石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (4): 784-800.doi: 10.11743/ogg20210402

• 油气地质 • 上一篇    下一篇

四川盆地上三叠统沉积储层研究进展与热点分析

施振生1(), 朱筱敏2,*(), 张亚雄3, 金惠1   

  1. 1. 中国石油 勘探开发研究院, 北京 100083
    2. 中国石油大学(北京) 地球科学学院,北京 102249
    3. 中国石化 石油勘探开发研究院, 北京 100083
  • 收稿日期:2021-02-19 出版日期:2021-08-28 发布日期:2021-08-27
  • 通讯作者: 朱筱敏 E-mail:19777027@qq.com;xmzhu@cup.edu.cn
  • 作者简介:施振生(1976—),男,博士,高级工程师,石油地质。E-mail: 19777027@qq.com
  • 基金资助:
    国家科技重大专项(2017ZX05035-001)

Advances and trending topics in sedimentary reservoir research ofthe Upper Triassic Xujiahe Formation, Sichuan Basin

Zhensheng Shi1(), Xiaomin Zhu2,*(), Yaxiong Zhang3, Hui Jin1   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
    2. College of Geosciences, China University of Petroleum, Beijing 102249, China
    3. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
  • Received:2021-02-19 Online:2021-08-28 Published:2021-08-27
  • Contact: Xiaomin Zhu E-mail:19777027@qq.com;xmzhu@cup.edu.cn

摘要:

四川盆地上三叠统天然气资源丰富,常规气藏和非常规气藏共存,等时地层格架下的沉积储层控制了天然气资源时空分布和富集。随着天然气勘探不断深入,沉积储层研究不仅体现了重要的科学意义和战略价值,而且取得了显著进展。在建立四川盆地上三叠统层序地层格架基础上,确定了前陆盆地对称型和不完全对称型结构层序地层样式及演化模式。四川盆地马鞍塘组—须家河组三段(须三段)为海相沉积,须家河组四段(须四段)—须家河组六段(须六段)为陆相沉积,但仍受到海侵作用的影响。马鞍塘组主要发育礁滩相、潟湖相、潮坪相和三角洲相,小塘子组主要发育障壁砂坝-潟湖沉积,盆地周缘发育小型三角洲。川西须家河组须二段、须四段和须六段主要发育冲积扇、扇三角洲和辫状河三角洲沉积,须三段主要发育滨海-三角洲沉积,须五段主要发育湖泊-三角洲沉积。晚三叠世四川盆地存在秦岭古陆、大巴山古陆、松潘-甘孜褶皱带(古龙门山)、康滇古陆和江南(雪峰)古陆等5大物源区,不同物源区的物源性质、影响范围和程度均存在巨大差异。整体上,须二段-须三段沉积时期,物源主要来自于盆地北部,其他方向物源影响范围相对较小。须家河组发育致密砂岩储层,压实作用造成本地区砂岩原生孔隙度大幅度减小, Ⅱ期和Ⅲ期石英加大进一步减小原生孔隙,封闭的地下流体环境是储层保持致密化的又一原因。须家河组甜点储层的形成受沉积微相、溶蚀作用,绿泥石衬边和裂缝控制,三角洲前缘水下分支河道砂体为有利沉积微相。近年来,浅水三角洲研究和页岩气勘探开发取得重大进展,四川盆地上三叠统浅水三角洲、细粒沉积学及沉积机理、沉积过程模拟、细粒沉积储层特征及其成因机制是目前研究的热点领域及未来发展方向。

关键词: 层序地层, 海侵过程, 细粒沉积, 致密储层, 沉积体系, 上三叠统, 四川盆地

Abstract:

The Upper Triassic in the Sichuan Basin is rich in both conventional and unconventional gases, the temporal and spatial distribution and enrichment of which are controlled by sedimentary reservoirs under an isochronous stratigraphic framework.Exploration activities in the basin have drawn greatly from sedimentary reservoir research and highlighted its scientific and strategic significance.Progresses made in the domain can be summarized as establishment of symmetrical and less symmetrical sequence stratigraphic models and their evolutionary patterns of the foreland basin based on previous Upper Triassic sequence stratigraphic frameworks.The Ma'antang Formation to the third member of Xujiahe Formation are marine deposits, and the fourth to the sixth member of Xujiahe Formation are continental deposits, though still under the effect of sea transgression.The Ma'antang Formation mainly consists of reef-shoal facies, lagoon facies, tidal flat lake and delta facies; the Xiaotangzi Formation mainly consists of barrier sand bar-lagoon facies with small deltas developed around basin.The second, fourth and sixth members of Xujiahe Formation are dominated by alluvial fans, fan deltas and braided river delta facies, the third member consists of costal-delta facies, and the fifth member is mainly composed of lacustrine-delta facies.Five major provenances existed during the Late Triassic in Sichuan Basin, including Qinling ancient land, Dabashan ancient land, Songpan-Ganzi fold belt, Kangdian ancient land, and Jianglan ancient land, with each providing sediment inputs of temporal and spatial differences in terms of nature, scope and extent.Sediments were largely sourced from the north part of the basin during the deposition of the second and third members of Xujiahe Formation.Tight sandstone reservoirs in the Xujiahe Formation are closely linked to compaction which caused great primary porosity loss and the quartz overgrowth in Ⅱ and Ⅲ phases that further reduced the primary porosity.The closed underground fluid environment also made its contribution to the formation of tight reservoirs.Sweet spots in the formation were controlled by microfacies, dissolution, chlorite lining, and fractures, and thus making the underwater branch channels at delta fronts the most promising targets for tight gas discovery.With major progresses in shallow water delta research and shale gas exploration in recent years, shallow water deltas, fine-grain sedimentology and deposition mechanisms, sedimentary process simulation and fine-grained reservoir characterization of the Upper Triassic in Sichuan Basin, have become the trending topics and future research directions.

Key words: sequence stratigraphy, transgressive process, fine-grained deposits, tight reservoir, depositional system, Upper Triassic, Sichuan Basin

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